Study On Water Inrush Characteristics Of 5~# Coal Seam Floor In Liujialiang Coal Mine

Coal mine water disaster is one of the main disasters in the process of coal mine construction and production.The study of coal mine water disaster is of great significance to prevent coal mine accidents.Taking the floor water inrush of Liujialiang mine field as the main research content,the main control factors of water inrush from the floor of No.5 coal seam in Liujialiang mine field are studied,and evaluates the risk of floor water inrush of coal seam and tunnels by means of sorting and analyzing mine hydrogeological data,field survey,sample collection,lithology identification,rock sample mechanical test and numerical simulation;Taking the water inrush accident of 5137 tunnel as the engineering background,the water inrush characteristics of fractured floor is discussed.The main conclusions are as follows:（1）Through sorting out and analyzing the previous geophysical exploration and drilling data,it is clear that there is no large fault structure and collapse column in the water resisting layer of the floor of 5137 tunnel;Through the macroscopic and microscopic identification of the rock samples of the floor water resisting layer,the lithologic characteristics and mineral composition of the rock samples are determined;The uniaxial compressive strength and uniaxial tensile strength of the rock sample of the floor water resisting layer are measured by rock mechanics test.The uniaxial compressive strength is 14.01～89.45MPa and the uniaxial tensile strength is 1.37～5.03MPa.（2）Taking the water inrush accident of 5137 tunnel in Liujialiang mine field as the engineering background,the process of the activation and expansion of the cracks and the formation of the water diversion channel when the roadway working face pushes through the floor with cracks is reproduced by using FLAC/FLAC^3D software.It is concluded that the original rock stress balance state of the floor rock is destroyed after the roadway excavation,the stress concentration phenomenon will appear at both ends of the working face and at the top and bottom of the crack,and the floor aquiclude will gradually form a"saddle shaped"mining failure zone;Under the influence of ground pressure,the fracture will expand upward due to shear failure.For the floor fractures with the same vertical height,the smaller the inclination angle,the easier it is to activate and expand to form a water inrush channel.（3）The main controlling factors of water inrush from the floor of No.5 coal seam in Liujialiang mine field are comprehensively analyzed,and the factors affecting water inrush are summarized into four aspects:the influence of aquifer on water inrush from the floor is mainly manifested in water pressure and water yield;The influence of ground pressure on water inrush from the floor is mainly manifested in the depth of mining failure of the floor;The influence of floor water resisting layer on floor water inrush is mainly manifested in the thickness of floor water resisting layer,the thickness of effective water resisting layer and the total compressive strength of floor water resisting layer;The influence of geological structure on water inrush from the floor is mainly represented by faults and folds.In addition to the water abundance of the aquifer,each water inrush factor is quantified and the contour map is drawn.（4）The"five figure and two coefficient method"is used to evaluate the water inrush in No.5 coal seam in Liujialiang mine field.The mine field is divided into the relatively safe zone of mining under pressure in the southeast,the transition zone of mining under pressure in the middle and the dangerous zone of mining under pressure in the northwest.The zoning map of evaluation of mining under pressure in No.5 coal seam in Liujialiang mine field is obtained;At the same time,the maximum water pressure that the floor water resisting layer of No.5 coal seam;Finally,combined with the actual situation of Liujialiang project,some suggestions on water control measures during roadway excavation,before mining,during mining and after mining are put forward.